Emulation and failure injection, a complement to Radiation Testing

Talk summary:

Accelerators are the accepted method to validate a device to flight. In vivo testing is a complex Emulation and failure injection, a complement to Radiation Test and expensive task that is needed to get information about how failures can propagate to primary outputs and monitor that the response of a design is correct.

There is a strong dependence between the design and test stimuli and the number of errors collected in a test of a complex circuit.

Fault Injection is an inexpensive technique that during design time, refine the design for the test fixture, improve the quality of stimuli, in order to maximize the error rate, and test the design observability.

The talk will present a practical tool useful for the design behavior prediction, in order to help to develop a good mitigation scheme and to develop a good test plan. This tool is also suitable to develop test plan for FPGAs.

Speaker:

Miguel A. Aguirre is a Professor in the area of Electronic Technology in the Universidad de Sevilla, in the Escuela Técnica Superior de Ingeniería. He has leaded at least five projects in the Spanish research plan and four European framework projects. He has addressed three PhD dissertation related to radiation testing. The research group headed by Prof. Aguirre has developed the fault injection system used by ESA called FT-UNSHADES2 and its analog version called AFTU.

Emulation and failure injection, a complement to Radiation Test

Principles of Fault Injection

Emulate the particle hitting using a controlled process in an FPGA as design support device.

The injected fault is a model of the physical effect under study.

After an injection the result is recorded into a Fault Dictionary.
The procedure is repeated a significant number of RUNS. This is called CAMPAIGN.

Fault models

REMARK: This mode of Fault Injection is done over the USER REGISTERS:

SEU -> Simple bit flip
MBU -> Several simultaneous bit flips paired by the layout
SET -> Several simultaneous bit flips capturing the transient pulse propagated through the logic cones and captured by the registers.

Contributions of FI to Radiation Testing: Diagnostic

The Workload can be improved using fault injection
HASH codes are used to detect and diagnose faults
SpaceWire Codec IP core
◦ 56% of errors are univocal
◦ 7% of errors have two candidates
◦ 37% of errors have

Faults on configuration memory

Faults are permanent modification of the circuit
Faults (in principle) do not propagate to other configuration memory cells
Faults are related or unrelated to the configured circuit.
Faults related:
• Produce an electrical influence
• Critical -> Can be compensated by
• Propagates to other configuration points

Xilinx produces part of this information in the “essential bits” file

Conclusions

Fault injection is an useful technique to predict circuit behaviour under radiation
A tool that produces prelimar results about the cross section of a design FT-UNSHADES2 is a Fault Injection tool simple, ubiquotous and flexible